System and Methods for a Foaming Process

ABSTRACT

A foaming process and a method for operation of the foaming process are provided. The method includes flowing a molten polymeric material into a mold from an upstream device, receiving the molten polymeric material in a cavity of the mold, and maintaining a repeatable, uniform pressure profile as the molten polymeric material is delivered into the mold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 16/687,531, filed on Nov. 18, 2019, and titled “SYSTEM ANDMETHODS FOR A FOAMING PROCESS,” which claims priority to U.S.provisional patent app. No. 62/770,709, filed on Nov. 21, 2018, andtitled “SYSTEM AND METHODS FOR A FOAMING PROCESS.” The entire contentsof each of the aforementioned applications is incorporated herein byreference.

FIELD

The present description relates generally to methods and systems formolding a polymer material.

BACKGROUND

Injection molding systems may be used to inject a foamed polymermaterial to form polymer products. The injection molding process may beautomated for cost-effective manufacturing of polymer goods. A qualityof the products may be dependent upon physical conditions of theinjection molding process.

SUMMARY

Injection molding systems may be used for cost-effective and efficientproduction of polymer goods. The manufacturing process may includeinjecting a foamed polymer material into a mold, a process that isperformed by an automated system. Automation of the injection moldingprocess may, however, lead to variations in physical conditions such aspressure changes at a nozzle of a device used to inject a moltenmaterial to form the foamed polymer material. Additionally, atemperature of the molten material may fluctuate, adversely affecting afoaming of the polymer material. Variability in the pressure and/ortemperature may lead to inconsistencies in cell size, expansion ratio,and mechanical properties of the polymer product. One method of reducingvariability between injection molded polymer products may includecontrolling the nozzle pressure of the injecting device by adjusting aninjection rate of the molten material into a mold cavity to maintain thenozzle pressure along a pre-set pressure profile during the moldingprocess. Another method may include maintaining a temperature of themolten material, the molten material stored in an injecting device, at apre-set melt temperature.

It should be understood that the summary above is provided to introducein simplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded view of an article of footwear including a solestructure that may be formed by an injection molding system.

FIG. 2 shows an example of an automated injection molding machine thatmay be used to form a sole structure of an article of footwear.

FIG. 3 shows an example of an injecting device used in an injectionmolding machine to deliver a foamed polymeric material to a mold.

FIG. 4 shows an example of large pellets of a material that may be usedto form a foamed polymer material.

FIG. 5 shows an example of small pellets of a material that may be usedto form a foamed polymer material.

FIG. 6 shows an example of expansion of the polymer material duringformation of a sole structure for an article of footwear.

FIG. 7 shows an example of a graph comparing a plotted pressure profileof an injection molding process subjected to a pressure feedback loop toa plotted pressure profile of an injection molding process where thecavity mold pressure is not controlled.

FIG. 8 shows a scanning electron microscopy image of cells of a polymerproduct resulting from an injection molding process where the cavitymold pressure is not controlled.

FIG. 9 shows a scanning electron microscopy image of cells of a polymerproduct resulting from an injection molding process where a nozzlepressure of an injecting device is controlled.

FIG. 10 shows an example of a routine for forming an injection moldedproduct using a pressure feedback system to adjust a fill rate based onnozzle pressure.

FIG. 11 shows an example of a routine for forming an injection moldedproduct using a temperature feedback system to adjust a temperature of amolten polymeric material flowed into mold cavities.

DETAILED DESCRIPTION

The following description relates to systems and methods for controllingphysical parameters, such as pressure and temperature in an automatedinjection molding process. The injection molding process may be used toform polymer products, such as a sole structure of a shoe, as shown inan exploded view of the shoe in FIG. 1 . Formation of polymer productsmay be accomplished by an automated injection molding machine. Anexample of the injection molding machine is shown in FIG. 2 , comprisinga plurality of molds arranged in a row. A foamed, molten polymermaterial may be injected into cavities of the plurality of molds by aninjecting device, as shown in FIG. 3 . The polymer material may be ablend of two or more types of pellets, the types of pellets havingdifferent compositions and/or sizes that form a single phase solutionupon melting in the injecting device. Examples of two different types ofpellets that may be used to form the polymer material are shown in FIGS.4 and 5 . The molten polymer material may expand upon curing, to largerdimensions than the cavity of the mold into which the material isinjected. Expansion of the sole structure of the shoe relative to themold is depicted in FIG. 6 . A graph is shown in FIG. 7 , plottingpressure profiles of nozzles of injecting devices during an injectionmolding process where cavity nozzle pressure is controlled by adjustingan injection rate of polymer material into the mold cavity and during aninjection molding process where the nozzle pressure is not regulated.Scanning microscopy images comparing a cellular distribution in theproducts of the two processes of FIG. 7 are shown in FIGS. 8 and 9 .Example routines describing injection molding processes using a pressurefeedback system to adjust a fill rate into the mold cavity and using atemperature feedback system to regulate a temperature of the moltenpolymeric material within the injecting device are depicted in FIGS. 10and 11 , respectively.

Injection molding may be used to manufacture various polymer-basedproducts, a process that may provide a variety of benefits such asformation of complex geometries and details, high production output,adaptability to different materials, decreased material waste, enhancedcontrol over product color, and ease of conversion to automation. Suchbenefits may leveraged for fabrication of sole structures for footwear,where a molten polymer, configured to foam and expand, is injected intoa mold that determines a shape of the sole structure. Once cured, thesole structure expands when released from the mold, the amount ofexpansion dependent on a combination of parameters including polymercomposition, cellular structure, and polymer temperature.

The process for forming injection molded sole structures has beenplagued with inconsistent results due to inadequate control over theinjection molding process. For example, fluctuations in pressure andtemperature during the process may lead to variations in cell size ofthe polymer material, in skin thickness and density, as well as inmechanical properties such as strength, stiffness, and surface qualityof the products. In addition, variability in an expansion ratio of thepolymer material due to inconsistent physical conditions duringfabrication may result in unpredictable and variable sole structuresize.

The inventors have recognized the aforementioned problems and havedeveloped systems and methods for injection molding of foamed polymermaterials which may achieve objectives that at least partially overcomethe issues. One of the objectives may be to maintain repeatable,consistent physical parameters during the injection molding process toreduce variability between products formed via a single method. In oneexample, the objectives are at least in part achieved via a method formolding a sole structure. The method includes flowing a molten polymericmaterial into a mold from an upstream device and receiving the moltenpolymeric material in a cavity of the mold. The method further includesmaintaining a repeatable, uniform pressure profile of the nozzle of thedevice while the material is delivered into the mold. By flowing thematerial into the mold while maintaining the pressure profile,variability between consecutive formations of polymer products formed bythe method may be reduced. As a result, control of the dimensions andphysical properties of the injection molded products may be improved. Inone example, the method may include detecting a pressure in the cavityof the mold during injection of the molten polymeric material. Inresponse to the detected pressure, the flow of molten polymeric materialinto the cavity may be adjusted in order to maintain a desired pressureaccording to a predetermined pressure profile. In such an example, anintroduction of polymer material to the initially empty cavity maygenerate backpressure that leads to fluctuations in nozzle pressure.Such fluctuations may be accounted for by providing a closed pressuresensing loop that allows for regulation of a fill rate of the moldcavity

In another example, a method is provided for molding a sole structure.The method includes maintaining a melt temperature of a polymericmaterial in an injection device by adjusting heating of the injectiondevice automatically responsive to sensed temperature. The methodfurther includes injecting the polymeric material from the injectiondevice into a cavity of a mold. By adjusting the temperature of thepolymeric material to remain at the melt temperature, a physical stateof the polymeric material is held consistent throughout a moldingprocess. In one example, maintaining the melt temperature of thepolymeric material includes delaying injection into the cavity of themold until the temperature returns to the melt temperature. In this way,uniformity between successively molded sole structures may be achieved.

In another example, a system is provided for forming a sole structure ofa shoe. The system includes an injecting device configured to inject amolten polymeric material, adapted with a pressure sensor, and a moldwith a cavity to receive the molten polymeric material from theinjecting device. In one example, the system may include detecting apressure in a nozzle of the upstream device. In such an example, apressure sensor may be provided at the nozzle and signals obtained fromthe sensor may be used to adjust a flow rate of polymeric material intothe mold to achieve and maintain a desired pressure profile of thenozzle. The flow rate may be adjusted by adapting the injecting devicewith a screw that is electronically adjusted in response to the detectednozzle pressure.

In another example, an injection molding system is provided. Theinjection molding system includes a plurality of molds arranged in aplurality of chambers arranged adjacently in a row and at least twoautomated injecting devices, the injecting devices adapted to couple toports in the plurality of molds. The injection molding system alsoincludes a molten polymeric material delivered to the plurality of moldsby the injecting devices, where injection from the injecting devices isindependently controlled to maintain a desired pressure profile duringinjection. In one example, the injection molding system is adapted witha controller including instructions stored in memory executable by aprocessor to operate a temperature and pressure control assembly. Thetemperature and pressure control assembly is configured to adjust thetemperature of the polymeric material and to control pressure in anozzle in each of the injecting devices. A consistent and repeatablecontrol of the temperature of polymeric material and pressure of thenozzles is thus achieved. This new system and approach creates a newarchetype of manufacturing quality control and presents new methods toachieve a significantly different result.

FIG. 1 shows an exploded view of an article of footwear 100 having anupper 102 and a sole structure 104 (hereafter referred to as the sole104). Therefore, the upper 102 may be referred to as a footwear upperand the sole 104 may be referred to as a footwear sole 104, in someexamples. It will be appreciated that at least a portion of the sole 104may be formed by a molding system and method, discussed above withregard to FIGS. 2-11 . The upper 102 is also at least partiallyconstructed out of a natural and/or synthetic leather material. Theupper 102 is also shown including a lacing section 106, a tongue 108, atoe section 110, and a heel section 112. However, it will be appreciatedthe article of footwear may include numerous additional or alternativesections. Moreover, different sections of the upper 102 may be formedfrom different materials. For instance, the lacing section 106 may beconstructed out of a synthetic material while sections below the lacingsection may be constructed out of a natural leather material. However,at least a bite line 113 and/or an underside 115 of the upper 102 mayinclude natural and/or synthetic leather material. The differentsections of the upper 102 may be attached via stitching, adhesiveattachment, fabric welding, etc.

The sole 104 may include an outsole 114 which may be constructed out ofa resilient material designed to contact an external surface (e.g.,road, trail, floor, etc.). The resilient material may include rubber, anelastomeric material, etc. The sole 104 may also include a midsole 116providing cushioning to the article of footwear 100. The midsole 116 maybe constructed out of materials such as ethylene-vinyl acetate (EVA)foams, PU foams, etc. It will be appreciated that the sole may includeother components such as cushioning components (e.g., airbags),protective components (e.g., plates), etc.

At least a portion of the sole 104, such as the midsole 116, may beformed through a process where a polymeric material configured to foam,such as EVA, is injected into a mold. The polymeric material may bemixed with a chemical or physical blowing agent that initiates foamingand expansion of the material. Release of the product from the moldallows the product to expand following a curing period where polymers ofthe polymeric material are cross-linked to provide rigidity andstructure to the product. The product may expand by an amount that isdependent upon a composition of the polymeric material, a balancebetween the polymeric material and blowing agent, and physicalconditions during the injection molding process, such as temperature andpressure.

The injection molding process may be conducted in an automated systemthat allows for formation of multiple products in-line. An example of anautomated molding system 200 (e.g., injection molding system) is shownin FIG. 2 . Although the molding system 200 is depicted with a pluralityof molds enclosed in chambers arranged in a row, other embodiments mayinclude variations in the form, profile, orientation, etc., ofcomponents of the molding system 200. Furthermore, it will beappreciated that a control of physical parameters of the molding systemmay be applied to other systems where it is desirable to adjust atemperature and/or pressure in a chamber housing a molten polymericmaterial.

The molding system 200 may be a multi-station apparatus including aplurality of chambers 202 arranged in a row. Chamber windows 204 of theplurality of chambers 202 are arranged on a front-facing side 206 of themolding system 200. The chamber windows 204 provide a view of componentsenclosed within each of the plurality of chambers 202 and also may beconfigured to slide open to allow access to interiors of each of theplurality of chambers 202. The front-facing side 206 of the moldingsystem 200 may also include a plurality of vents 208 for air exchangebetween an interior of the molding system 200 and surrounding ambientair, control panels 210 adjacent to each of the chamber windows 204,doors 212 for accessing mechanical and electronic components of themolding system 200 and window panels 214 for viewing a status of themechanical and electronic components. The doors 212 and window panels214 may be positioned at extreme ends of the molding system 200.

Each of the plurality of chambers 202 may include molds 216 housedwithin the interiors of the plurality of chambers 202. The molds 216each comprises an upper plate 218 and a lower plate 220 that may bestacked, e.g., the upper plate 218 directly over and in contact with thelower plate 220, to enclose cavities of the molds 216. The cavities arehollow chambers shaped according to a desired geometry of the injectionmolded product and adapted to receive the foamed polymeric material froman injecting device through inlet ports in the molds 216. The upperplate 218 and lower plate 220 are separated when curing of the polymericmaterial is complete to allow the molded product to be removed. Physicalconditions of the molds 216, such as temperature and pressure, may becontrolled by temperature and pressure control assemblies, receivingcommands from a computing device 222 communicatively coupled to theplurality of chambers 202.

The computing device 222 is included in the molding system 200 which maybe a controller configured to adjust various aspects of the moldingprocess. The computing device 222 includes a memory 224 and a processor226. The memory 224 may include volatile, nonvolatile, non-transitory,dynamic, static, read/write, read-only, random-access,sequential-access, location-addressable, file-addressable, and/orcontent-addressable devices. Additionally, the processor 226 may be asingle-core or multi-core device, and the instructions executed thereonmay be configured for sequential, parallel, and/or distributedprocessing. Although the computing device 222 is shown directly coupledto the plurality of chambers 202, the computing device 222 may beremotely located, in other instances. In such an example, the computingdevice 222 may be electronically (e.g., wired and/or wirelessly)connected to the plurality of chambers 202 and other components in thesystem.

The computing device 222 also includes a display device 228. The displaydevice 228 may be used to present a visual representation of data heldby the memory 224. The graphics presented on the display device 228 maytake the form of a graphical user interface (GUI) and/or other suitableinterfaces, for instance. The computing device 222 also includes aninput device 230. In the illustrated example, the input device 230 is inthe form of a keyboard. The input device may additionally oralternatively include a mouse, joystick, camera, microphone,touchscreen, combinations thereof, etc. Thus, user input may be used toadjust different aspects of the molding process, in some examples.Additionally or alternatively, automated instructions may triggerchanges in the molding process. Furthermore, the display device and/orthe input device may be omitted from the computing device, in otherembodiments.

The computing device 222 may also include a condition indicator 232which may indicate that the molding system 200 has reached one or moredesired operating condition(s) (e.g., shot tuning chamber pressureand/or temperature set-points, mold temperature set-points, mold counterpressure set-points, combinations thereof, etc.). Thus, the conditionindicator 232 may indicate to a system operator that a desired conditionhas been achieved such as a desired nozzle pressure of devices used toinject material into the molds 216. Responsive to the conditionindicator being triggered the system operator may command the system totake a desired action via the input device 230, such as adjusting aninjection rate of the molten polymeric material into the mold cavity.The condition indicator 232 may include audio, graphical, and/or hapticcomponents for alerting the system operator. The graphical indicator maybe included in the display device and/or may include one or morelight(s) for signaling the operator. In this way, certain aspects of themolding process may be manually controlled. However, in other examples,more automated control strategies may be utilized.

Sensors 234 may also provide signals to the computing device 222. Thesensors may include temperature sensors, pressure sensors, etc. Thesensors may be attached to or integrated into the injecting deviceand/or downstream components such as the plurality of chambers 202,described in more detail herein with regard to FIGS. 3-11 . Forinstance, the injecting device and/or the plurality of chambers 202 mayinclude temperature sensor(s), pressure sensor(s), and/or combinedtemperature—pressure sensor(s) sending signals to the computing device222. The sensors enable the temperatures and pressures in selectedsections of the system to be determined.

In some examples, the temperature and/or pressure in selected sectionsof the system may be determined (e.g., estimated) from temperatureand/or pressure sensor readings in other sections of the system.Additionally, instructions (e.g., code) stored in the memory 224 of thecomputing device 222 may include instructions for implementing themolding methods, processes, techniques, control schemes, etc., describedherein. As such, instructions may be stored in the memory 224 that causethe processor 226 to implement the actions, steps, features, etc., ofthe molding system described herein.

An example of an injecting device 300 is illustrated in FIG. 3 that maybe an additional component in a molding system, such as the moldingsystem 200 of FIG. 2 . In one example, the molding system may include asingle injecting device to deliver a polymeric material to a pluralityof molds. In other examples, however, the molding system may have two ormore injecting devices, individually operated to inject the polymericmaterial into distinct individual molds of the plurality of molds. Byconfiguring the molding system with two or more injecting devices, aspeed of production may be increased.

The injecting device 300 may be an elongate, tubular apparatus with aninner chamber 303. The injecting device 300 may be used to inject amolten polymeric material, configured to foam, into molds, such as themolds 216 of FIG. 2 . The polymeric material may be delivered to theinner chamber as a solid phase, such as pellets or beads, by a reservoir305 that is positioned above and coupled to a barrel 312 of theinjecting device 300. The reservoir 305 is proximate to a first,upstream end 304 of the injecting device 300 and configured with afunnel-like geometry.

The polymeric material includes one or more thermoplastic polymers. Theone or more thermoplastic polymers may include a thermoplastic elastomer(TPE). The one or more thermoplastic polymers may include aliphaticpolymers, aromatic polymers, or mixtures of both. As an example, the oneor more types of thermoplastic polymers may include a first typecomprising large pellets, such as shown by large polymer pellets 400 ofFIG. 4 . The large polymer pellets 400 may be mixed with another type ofthermoplastic polymer formed from small pellets, such as small polymerpellets 500 of FIG. 5 . The large pellets 400 may have a differentchemical composition from the small pellet 500. A relative proportion ofthe differently sized pellets may affect an overall composition of thepolymeric material, as well as physical conditions such as melttemperature, viscosity, flexibility, etc.

In one example, the one or more thermoplastic polymers may includehomopolymers, copolymers (including terpolymers), or mixtures of both.The copolymers may be random copolymers, block copolymers, alternatingcopolymers, periodic copolymers, or graft copolymers, for instance. Theone or more thermoplastic polymers may include olefinic homopolymers orcopolymers or a mixture of olefinic homopolymers and copolymers.Examples of olefinic polymers include polyethylene (PE) andpolypropylene (PP). For example, the PE may be a PE homopolymer such asa low density PE or a high density PE, a low molecular weight PE or anultra-high molecular weight PE, a linear PE or a branched chain PE, etc.The PE may be an ethylene copolymer such as, for example, anethylene-vinyl acetate (EVA) copolymer, an ethylene-vinyl alcohol (EVOH)copolymer, an ethylene-ethyl acrylate copolymer, an ethylene-unsaturatedmono-fatty acid copolymer, etc. The one or more thermoplastic polymersmay include a polyacrylate such as a polyacrylic acid, an ester of apolyacrylic acid, a polyacrylonitrile, a polyacrylic acetate, apolymethyl acrylate, a polyethyl acrylate, a polybutyl acrylate, apolymethyl methacrylate, a polyvinyl acetate, etc., includingderivatives thereof, copolymers thereof, and any mixture thereof, in oneexample. The one or more thermoplastic polymers may include an ionomericpolymer. The ionomeric polymer may be a polycarboxylic acid or aderivative of a polycarboxylic acid, for instance. The ionomeric polymermay be a sodium salt, a magnesium salt, a potassium salt, or a salt ofanother metallic ion. The ionomeric polymer may be a fatty acid modifiedionomeric polymer. Examples of ionomeric polymers include polystyrenesulfonate, and ethylene-methacrylic acid copolymers. The one or morethermoplastic polymers may include a polycarbonate. The one or morethermoplastic polymers may include a fluoropolymer. The one or morethermoplastic polymers may include a polysiloxane. The one or morethermoplastic polymers may include a vinyl polymer such as polyvinylchloride (PVC), polyvinyl acetate, polyvinyl alcohol, etc. The one ormore thermoplastic polymers may include a polystyrene. The polystyrenemay be a styrene copolymer such as, for example, an acrylonitrilebutadiene styrene (ABS), a styrene acrylonitrile (SAN), a styreneethylene butylene styrene (SEBS), a styrene ethylene propylene styrene(SEPS), a styrene butadiene styrene (SBS), etc. The one or morethermoplastic polymers may include a polyamide (PA). The PA may be a PA6, PA 66, PA 11, or a copolymer thereof. The polyester may be analiphatic polyester homopolymer or copolymer such as polyglycolic acid,polylactic acid, polycaprolactone, polyhydroxybutyrate, and the like.The polyester may be a semi-aromatic copolymer such as polyethyleneterephthalate (PET) or polybutylene terephthalate (PBT). The one or morethermoplastic polymers may include a polyether such as a polyethyleneglycol or polypropylene glycol, including copolymers thereof. The one ormore thermoplastic polymers may include a polyurethane, including anaromatic polyurethane derived from an aromatic isocyanate such asdiphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI), or analiphatic polyurethane derived from an aliphatic isocyanate such ashexamethylene diisocyanate (HDI) or isophone diisocyanate (IPDI), or amixture of both an aromatic polyurethane and an aliphatic polyurethane.

Optionally, in addition to the one or more thermoplastic polymers, thepolymeric material may further include a crosslinking agent. Thecrosslinking agent may be a peroxide-based crosslinking agent such asdicumyl peroxide. Optionally, in addition to the one or morethermoplastic polymers, the polymeric material may further include oneor more fillers such as glass fiber, powdered glass, modified or naturalsilica, calcium carbonate, mica, paper, wood chips, modified or naturalclays, modified or unmodified synthetic clays, talc, etc.

Specifically, in one example, the polymeric material may include EVAand/or thermoplastic polyurethane (TPU) and the molding system maycreate a molded footwear component (e.g., upper, midsole, and/oroutsole). However, the molding system and processes described hereinhave far-reaching applicability to fields beyond the footwear industrysuch as the automotive industry, aerospace industry, packaging industry,sporting goods industry, etc. Therefore, the molding system may bedesigned to manufacture a wide variety of articles in any of theaforementioned fields. As described herein, an article may be anyobject, part, component, product, etc., used any of the aforementionedindustries or in other suitable industries.

As the polymeric material enters the barrel 312 of the injecting device300, the polymeric material may be heated via heating devices 307coupled to the barrel 312. It will be appreciated that the heatingdevices 307 may increase a temperature of the barrel 312 which in turnmay increase a temperature of the polymeric material. The heatingdevices 307 may be controlled by the computing device 222 shown in FIG.2 .

A blowing agent delivery assembly 309 is also coupled to the barrel 312of the injecting device 300 at a region downstream of the heatingdevices 307 and upstream of a nozzle 306 at a second end 308 of theinjecting device 300, the second end 308 downstream of the first end304. The blowing agent delivery assembly 309 includes a blowing agentstorage device 311 and a blowing agent valve 313. A blowing agentconduit 315 extends between the blowing agent valve 313 and blowingagent storage device 311. The blowing agent valve 313 is adapted toadjust an amount of blowing agent flowing into the barrel 312. Forinstance, the blowing agent valve 313 may be opened/closed to allow theblowing agent to be flowed into the barrel 312 during certain operatingconditions and to prevent the blowing agent from flowing into the barrelduring other operating conditions. Moreover, the blowing agent valve 313may have a plurality of different open positions allowing the flowrateof the blowing agent delivered to the barrel 312 to be adjusted.

Another blowing agent conduit 317 extends between the blowing agentvalve 313 and the barrel 312. Specifically, the blowing agent conduit317 opens into the inner chamber 303 of the barrel 312 having a screw310 housed therein. The blowing agent may be flowed into the moltenpolymeric material in the barrel to form a molten single phase solution(SPS). The molten SPS may therefore include the molten polymericmaterial and a blowing agent dissolved therein, in some examples.

The blowing agent may be a chemical blowing agent which forms a gas whenheated. For example, the chemical blowing agent may be an azo compoundsuch as adodicarbonamide, sodium bicarbonate, or an isocyanate that maybe mixed with the polymeric material in the barrel 312 of the injectingdevice 300. Alternatively, the chemical blowing agent may already beincorporated into pellets formed from a polymeric material andintroduced into the injecting device as a preformed mixture.

Other examples may include a physical blowing agent instead of or inaddition to the chemical blowing agent. Specifically, the blowing agentmay include nitrogen and/or carbon dioxide, in some examples. However,other suitable blowing agents may be used such as hydrocarbons (e.g.,pentane, isopentane, and/or cyclopentane), hydrochlorofluorocarbons(HCFCs), mixtures thereof, etc. Other examples may include a chemicalblowing agent. Furthermore, the blowing agent stored in the blowingagent storage device 311 may be stored and/or injected into the barrel312 as a supercritical fluid (SCF).

The injecting device 300 may include a drive motor 302 at the first end304. The drive motor 302 is coupled to the screw 310, the screw 310extending a portion of a distance between the first end 304 and secondend 308 of the injecting device 300 within the barrel 312 of theinjecting device 300. The screw 310 may be positioned within the barrel312 so that a tip 314 of the screw 310 is spaced away from an interiorsurface of the inner chamber 303 in a region where the nozzle 306 mergeswith the barrel 312.

The drive motor 302 may rotate the screw 310, as indicated by curvedarrow 316, and/or advance and retract the screw 310 in the barrel 312,as indicated by arrow 318. In one example, the drive motor 302 may be anelectric motor that provides screw adjustment functionality. Rotation ofthe screw 310 causes the SPS to flow downstream through the barrel 312.Advancement of the screw 310 in the barrel 312 toward the nozzle 306,induced by the drive motor 302, increases a pressure in the innerchamber 303 downstream of the tip 314 of the screw 310. The innerchamber 303 may be filled with the SPS and increasing the pressuredownstream of the tip 314 of the screw 310 increases a pressure of theSPS, pushing the polymeric material out of the barrel and through thenozzle 306. In other examples, separate actuators may be used to rotateand advance/retract the screw.

A section 326 of the barrel 312 downstream of the screw 310 accumulatesmolten polymeric material (e.g., molten SPS) during operation of theinjecting device 300. The section 326 may therefore provide a stagingarea housing both the molten polymeric material and the blowing agent.In another example, however, the section 326 may only house the moltenpolymeric material. In the illustrated example, a temperature sensor 328is shown arranged in the section 326 of the barrel 312 downstream of thescrew 310 and is in electronic communication with the computing device222, shown in FIG. 2 . The temperature sensor 328 is configured tomeasure a temperature of the molten polymeric material in the barrel312. In addition, a pressure sensor 330 is positioned in the nozzle 306of the injecting device to measure a pressure in the nozzle 306. Howeverin other examples, additional or alternative suitable sensor positionshave been contemplated, such as other locations between the nozzle 306and the screw 310. Still further in other examples, a single sensor maybe used to measure both temperature and pressure, additional temperatureand/or pressure sensors may be coupled to the barrel or other locationsin the system. Other sensors providing relevant information such astemperature, pressure, etc. may also be positioned within a mold 327 orwithin runners or gates of an automated molding system, such as theautomated molding system 200 of FIG. 2 .

The nozzle 306 of the injecting device 300 is adapted to couple to aninlet port 322 in a mold 327. In some examples, the nozzle 306 of theinjecting device 300 may include a valve (not shown in FIG. 3 ) that isactuatable between an open position to allow the SPS to flow from thenozzle 306 through the inlet port 322 into a cavity 324 of the mold 327,and a closed position to block flow through the nozzle 306 and retainthe SPS within the nozzle 306 and barrel 312 of the screw 310. The valvemay be adjusted into positions between the open position and the closedposition to regulate the flow of the SPS from the barrel 312 to thecavity 324, the position of the valve controlled by the computing device222 of FIG. 2 . However, in other examples, the injecting device 300 maynot include the valve in the nozzle 306 and flow of the SPS from thenozzle 306 into the mold 327 may be controlled exclusively by rotationof the screw 310 by the drive motor 302. Thus, the computing device mayuse information received from the pressure sensor 330 to vary theinjection rate of molten SPS in the mold cavity 324 to maintain apredetermined pressure profile based on a detected backpressuregenerated during filling of the cavity 324. Information from thetemperature sensor 328 may be used to regulate power supplied to theheating devices 307 to adjust the temperature of the barrel 312, andhence the temperature of the SPS, to maintain the temperature at a melttemperature of the polymeric material.

The temperature of the SPS during injection into the mold cavity and theconcurrent cavity pressure during the injection molding process may havesignificant effects on physical properties of the polymer product. Inone example, a consistency of an expansion ratio of the SPS following abaking, or curing period for a given composition may rely on arepeatability of pressure control of the mold cavity. The givencomposition may be a set ratio of large and small pellets, e.g., thelarge pellets 400 and small pellets 500 of FIGS. 4 and 5 respectively,as well as amount of blowing agent added. With the ratio of large tosmall pellets held constant, variations in the expansion ratio betweeninjection molded soles is attributable to physical parameters during theinjection molding process occurring in the mold. The molten SPS may beconfigured to expand when thermally or chemically induced polymercrosslinking occurs. The expansion of the product, relative to aninitial size determined by a cavity of a mold, is depicted in FIG. 6 byan example of a set of soles 600 that have been removed from a mold 602.

Expansion of the set of soles 600, formed from the SPS, within a cavity604 of the mold 602 is suppressed until the mold 602 is opened and anupper plate 606 is separated from a lower plate 608 of the mold. Thecavity 604 includes an upper portion 610 that is disposed in the upperplate 606 and a lower portion 612 disposed in the lower plate 608 of themold 602. The upper plate 606 may have a similar outer shape as thelower plate 608 with the upper portion 610 of the cavity 604 arranged ina bottom face 614 of the upper plate 606. The bottom face 614 of theupper plate 606 is in face-sharing contact with a top face 616 of thelower plate 608 when the upper plate 606 and lower plate 608 areassembled during an injection molding process. The upper portion 610 ofthe cavity 604 is positioned in the bottom face 614 of the upper plate606 and the lower portion 612 of the cavity 604 is positioned in the topface 616 of the lower plate 608 so that when the upper plate 606 and thelower plate 608 are in face-sharing contact, the upper portion 610 ofthe cavity 604 is aligned with and directly above the lower portion 612of the cavity 604.

The upper and lower portions 610, 612 of the cavity 604 may includegeometric patterns forming either protrusions or indentations alongsurfaces of the cavity 604 that are transferred to surfaces of the setof soles 600. For example, a top surface 618 of the set of soles 600 aredepicted in FIG. 6 with a pattern imprinted from the upper portion 610of the cavity 604. Side surfaces 620 of the cavity 604 may be texturedto impart a desired texturing or patterning to side surfaces 622 of theset of soles 600. Furthermore, the lower portion 612 of the cavity 604may be adapted with channels 624 branching from an inlet port 626, theinlet port 626 and channels 624 fluidly coupling air surrounding themold 602 to air inside the cavity 604.

The inlet port 626 may provide an opening to the cavity 604 of the mold602 into which the molten SPS is injected to fill at least a portion ofan inner volume of the cavity 604 when the mold 602 is assembled (e.g.,the upper plate 614 and lower plate 608 are in face-sharing contact).The inlet port 626 may be configured to couple directly to a nozzle ofan injecting device, such as the nozzle 306 of the injecting device 300of FIG. 3 . The nozzle may be inserted into the inlet port 626 to flowthe SPS into the cavity 604 through the inlet port 626 and channels 624with a minimal loss of material from leakage or spillage.

Upon releasing the cured, hardened polymeric material from the confinesof the cavity 604 after the baking period, the set of soles 600 mayincrease in size relative to a size of the cavity 604. For example, theset of soles 600 may expand to 110%, 145%, or 160% of the size of thecavity 604, depending on conditions imposed on the molten polymericmaterial during the injection molding process. As an example,differences in a final pressure between one cavity of one mold andanother cavity of another mold at completion of curing may result indifferent expansion ratios. Properties of the set of soles 600, such asdurability and flexibility, may show differences according to how muchthe SPS expands. Thus reducing and controlling variation in cavitypressure during the injection molding process may allow for increasedcontrol over the expansion ratio of the set of soles 600. The finalcavity pressure may be made uniform between molds by repeatablymaintaining a pressure profile at the injecting device nozzle duringinjection.

For example, a preferred expansion ratio may be 145%. A pressure profilefor the nozzle of the injecting device for a set composition of thepolymeric material may be estimated. The pressure of the nozzle duringinjection may be measured and used to adjust a flow rate of SPS into thecavity 604 to adhere to the predetermined pressure profile. A cavitypressure may be estimated based on the nozzle pressure, the nozzlepressure measured by configuring the nozzle of the injecting device witha pressure sensor, such as the pressure sensor 330 shown in FIG. 3 .Adapting the injecting device with the pressure sensor at the nozzle mayprovide instantaneous pressure feedback in a closed loop system thatallows a controller, such as the computing device 222 of FIG. 2 , toimmediately adjust an injection rate of the injecting device in responseto backpressure due to a rise in pressure in the mold cavity.

For example, rapid injection (e.g., rapid rotation of an electronicallycontrolled screw of an injecting device) of the SPS in the mold cavitymay generate backpressure due to a decreasing volume of the cavity.Detection of backpressure in the cavity may allow an immediate decreasein injection rate, dissipating excess pressure and returning the cavitypressure to a desired pressure. Conversely, if pressure in the cavity isdetected to decrease, due to a slow injection rate for example, theinjection rate may be increased until a target pressure is obtained. Thepositioning of the pressure sensor at the nozzle enables accuratemeasurement of the cavity pressure when the nozzle is inserted into theinlet port.

By maintaining a cavity pressure according to a pressure profile,repeatability of the cavity pressure during an injection molding processmay be achieved, resulting in a consistent expansion ratio of a polymerproduct. A graph 700 of a pressure of a nozzle of a first injectingdevice, such as the injecting device 300 of FIG. 3 , is shown in FIG. 7to illustrate an example of a first plot 702 of a pressure of theinjecting device nozzle (solid thick line) when the nozzle is adaptedwith a pressure sensor that provides pressure feedback to a controller,such as the computing device 222 of FIG. 2 . The controller may regulatean injection rate of a molten polymeric material (SPS) into a cavity ofa first mold by actuating a drive motor rotating a screw of theinjecting device nozzle and/or adjusting a position of a valve in thenozzle based on the pressure detected in the nozzle. The pressure may becompared to a preset pressure profile, specific to a temperature ortemperature range of the molten polymeric material or mold cavity, andthe injecting rate may be adjusted according to a deviation of themeasured pressure from the pressure profile.

An x-axis of the graph 700 displays time and a y-axis of the graph 700displays pressure. The first plot 702 shows the pressure in the nozzleof the first injecting device during formation of a polymer product,such as a sole structure of a shoe. The nozzle is inserted into an inletport in the first mold to flow the molten SPS, configured to foam andexpand, into the cavity of the first mold. The plot 702 of thepressure-feedback system is hereafter referred to as thepressure-feedback plot 702.

The pressure-feedback plot 702 is overlaid with a second plot 704 of ameasured pressure of a nozzle of a second injecting device during aformation of a polymer product. The molten SPS that is injected into thefirst mold is similarly injected into the cavity of a second mold by thesecond injecting device. The second injecting device is not configuredto provide real-time pressure measurements to the controller, however,and the nozzle pressure is not used as a sensory feedback to adjust aninjection rate of the polymeric material into the second mold.Hereafter, the plot 704 of the pressure in the second injecting deviceis referred to as the uncontrolled plot 704.

Four intervals are indicated in graph 700: T₁, T₂, T₃, and T₄. The firstinterval, T₁ is a period during which the polymeric material isintroduced to barrels of the injecting devices, heated to become molten,and injected into the cavities of the molds. The SPS foams and expandsin volume driving an increase in pressure in the molds and generatingbackpressure that is detected by the pressure sensors in the nozzles ofthe injecting devices. During T₁, the pressure in the nozzle of thefirst injecting device, shown by the pressure-controlled plot 702,increases rapidly due to the addition of SPS to a barrel of the firstinjecting device. The pressure plateaus quickly and remains relativelystable due to adjustment of the injection rate based on the pressurefeedback information. For example as backpressure increases, a rate offlow of SPS through the injecting device may be decreased to compensatefor the higher pressure in the nozzle, thus maintaining an overalluniform pressure at the nozzle.

The uncontrolled plot 704 also increases quickly as the barrel of thesecond injecting device is filled with the polymeric material. Theinjection rate is not adjusted and the pressure detected in the nozzleof the second injecting device spikes to a higher pressure than thepressure-controlled plot 702 due to backpressure as the cavity of thesecond mold is filled with SPS. The measured pressure graduallydecreases to a similar pressure as the pressure of plot 702 before theend of T₁.

At a start of T₂, a hold phase, both plot 702 and 704 decreases abruptlyas the flow of SPS in the molds ceases and the polymeric material is nolonger added to the barrels of the injecting devices. An estimatedcavity pressure of the first mold is represented by a dashed line ofplot 708, indicating that the cavity pressure begins to rise in thefirst mold at the start of T₂. The rise in cavity pressure is caused byinitiation of curing and expansion of the SPS. Curing is initiated byactivation of a cross-linking agent, spurring cell nucleation. Alow-pressure set-point is maintained in the first mold, resulting in auniform pressure in the first mold, as shown in plot 702 between T₂ andT₃. In contrast, pressure detected in the nozzle of the second injectingdevice drops to ambient levels, as shown by the uncontrolled plot 704.

A first estimated cavity pressure of the second mold is represented by adashed line in plot 710 and curing and expansion, indicated by a rise incavity pressure, does not begin until T₂ ends and T₃ begins. Curing ofthe SPS is faster in the first mold, as indicated by plot 708, than inthe second mold, as indicated by plot 710, due to the low-pressure setpoint imposed in the first mold once the mold is filled. The pressureforces the polymeric material to press against a wall of the first mold.The contact between the material and the wall of the first mold allowsmore rapid and even heat conduction through the polymeric material thanin the uncontrolled system depicted by plot 710.

At the end of T₂ the injecting devices are moved from the first andsecond molds to adjacent, empty molds. The removal of the firstinjecting device from the first mold results in a drop in the nozzlepressure of the first injecting device to ambient levels.

Curing of the SPS in the first mold, shown by plot 708, is complete whenT₃ ends (and T₄ begins). Expansion of the material terminates and thecavity pressure reaches a preset terminal pressure level. The pressurein the second mold, indicated by plot 710 as one example, continuesincreasing during T₄, reaching the terminal pressure level when T₄ ends.Significant variation in the curing period may occur arising fromvariations in pressure at the nozzle of the second injecting device. Forexample, a second estimated cavity pressure of the second mold is shownby a dashed line in plot 712. A rise in cavity pressure is delayedrelative to plot 710 and the pressure does not reach the terminalpressure level by the end of T₄. Instead, an extended period of time mayelapse before the cavity pressure represented by plot 712 achievescomplete curing.

The plots depicted in graph 700 show that the pressure-feedback systemallows curing of the SPS to be initiated earlier when a uniform nozzlepressure is maintained. In addition, the consistent nozzle pressureduring filling of the mold cavity may result in reduced variation inphysical attributes of the polymer product, such as skin thickness andcell size, between products formed in replicate molds. Uniformitybetween iterations of the polymer product may be further increased bycontrolling a temperature of the SPS.

Consistency in the properties of the injection molded polymer productmay be enhanced by maintaining a temperature of the molten polymericmaterial within a barrel of the injecting device at a melt temperatureof the material. The melt temperature may depend on a composition of thepolymeric material. For example, the melt temperature may vary accordingto a ratio of large and small pellets, such as the large pellets 400 andsmall pellets 500 shown in FIGS. 4 and 5 , and may also be affected byrelative amounts of blowing and crosslinking agents.

When the temperature of the barrel of the injecting device falls belowthe melt temperature, a viscosity of the SPS may increase, decreasing aflow rate of the SPS into the mold cavity and decreasing cavitypressure. When the temperature of the barrel rises above the melttemperature, overcooking of the SPS may occur, altering a cellularstructure of the SPS and degrading physical properties of the polymerproduct. For example, a viscosity of the SPS may be become greatlyreduced, affecting an ability of the material to foam and expand.Furthermore, fluctuations in barrel temperature above the melttemperature may lead to increased material waste due to purging of thebarrel in between injections to expel overcooked polymeric material fromthe injecting device.

A likelihood of temperature variability in the barrel of the injectingdevice may be reduced by adapting the injecting device with atemperature sensor in the barrel, such as the temperature sensor 328shown in FIG. 3 . The temperature sensor detects the temperature of themolten SPS in the barrel and sends the information to the controller.The controller may send a command to heating devices of the injectingdevice, such as the heating devices 307 of FIG. 3 , to adjust a powerdelivered to the heating device to produce a desired temperature of thebarrel. In this way, the temperature sensor, communicatively coupled tothe heating devices through the controller, provides a closed feedbacksystem to regulate the temperature of the barrel. If the barreltemperature decreases below the melt temperature, injection of the SPSmay be delayed until the temperature is increased to the targettemperature. A likelihood of exposure of the polymeric material totemperatures above the melt temperature is reduced. The temperaturefeedback allows the temperature of the barrel to be maintained at themelt temperature, thereby reducing an amount of wasted material due tooverheating of the polymeric material.

The feedback pressure system and the feedback temperature system may beused in combination in some examples, or used independently in otherexamples. Configurations of the injection molding system including bothpressure detection at the nozzle of the injecting device and temperaturemeasurement in the barrel may enable a high degree of conformity to aset of desired material properties of the polymer product. One suchproperty is cell size. As the SPS foams and expands, pockets of gas mayform within the material. The pockets of gas, or cells, are enclosedwithin layers of the polymeric material. Uniformity in flexibility,abrasion resistance, and tensile strength and other mechanicalproperties across an entirety of the polymer product may be attained bygeneration of similarly sized cells.

An example of a first cellular structure 800 of a polymeric materialproduced by an injection molding process is shown in a scanning electronmicroscope (SEM) image in FIG. 8 . The polymeric material with the firstcellular structure 800 may be formed without use of a pressure feedbacksystem or temperature feedback system as described above. The firstcellular structure 800 includes a plurality of cells 802 that exhibit arange of cell diameters. As shown in an exploded view 804 of the firstcellular structure 800, cell sizes vary between 174 microns in diameterto 235 microns.

A SEM image of an example of a second cellular structure 900 of apolymeric material is shown in FIG. 9 , depicting cells with a moreuniform a cell diameter and distribution. The second cellular structure900 is formed through an injection molding process where at least thepressure feedback system is applied and, in some examples, theadditional temperature feedback system is also employed. While somevariation in cell size is observed, an overall range in cell size isnarrower in the second cellular structure 900 than the first cellularstructure 800. Furthermore, a plurality of cells 902 of the secondcellular structure 900 has an overall smaller size, averaging 82 micronsin diameter, than the plurality of cells 802 of the first cellularstructure 800. The smaller size of the plurality of cells 902 of thesecond cellular structure 900 allows each cell to be surrounded by athicker layer, or skin, of polymeric material, thereby increasing astructural integrity of the plurality of cells 902 and of a polymerproduct formed from the polymeric material.

An example of a routine 1000 for an injection molding process to form apolymer product, such as a sole structure of a shoe, is shown in FIG. 10. A molding system of the injection molding process may include aplurality of molds with inner cavities arranged in a row of chambers,each chamber enclosing a mold of the plurality of molds. An automatedinjecting device, such as the injecting device 300 of FIG. 3 , may beconfigured with a barrel to receive and store a polymeric material(e.g., to form a SPS) mixed with a chemical blowing agent. In oneexample, the injecting device may include an additional crosslinkingagent, a screw to push the SPS through the injecting device that iselectronically controlled, and a nozzle adapted to couple to inlet portsin the mold. The nozzle of the injecting device may include a pressuresensor, such as the pressure sensor 330 of FIG. 3 to detect a pressureof the nozzle as the injecting device injects the SPS into the mold. Thepressure sensor and motor driving rotation of the screw may be adaptedto communicate electronically with a controller, such as the computingdevice 222 of FIG. 2 , configured to receive sensory information andsend commands to actuators of the molding system.

At 1002, the routine includes filling the barrel of the injecting devicewith a polymeric material with a pre-set blend of small and largepellets, including the polymeric material mixed with the chemicalblowing agent and the crosslinking agent, and providing a fixedcomposition of the material. The barrel is heated to melt the materialto form the molten SPS. The routine includes injecting the molten SPSinto the cavity of the mold at 1004. The pressure of the nozzle ismonitored by the pressure sensor at 1006 while the SPS is injected. Thenozzle pressure is relayed to the controller and compared to a presetpressure profile stored in a memory of the controller.

At 1008, the fill rate, or injection rate, is adjusted based on thedetected cavity pressure. For example, if the pressure is detected torise above a pressure setting of the pressure profile, the fill rate maybe decreased until the pressure returns to a target pressure. As anotherexample, if the cavity pressure decreases below the pressure setting ofthe pressure profile, the fill rate may be increased until the pressurereaches the target pressure.

At 1010, the routine includes curing the molten SPS. Curing the materialincudes either injecting a crosslinking agent, such as a peroxide, ifnot already added, or activating a crosslinking agent already mixed withthe polymeric material, to induce polymer cross-linking. Concurrent with1010, the controller commands a purging of remaining SPS stored in theinjecting device barrel at 1012. The injecting device is shifted to anadjacent mold at 1014, with the barrel of the injecting device filledwith fresh SPS, and returns to the start of the routine at 1002.

An example of a routine 1100 for an injection molding process to form apolymer product, such as a sole structure of a shoe, is shown in FIG. 11. A molding system of the injection molding process may include aplurality of molds with inner cavities arranged in a row of chambers,each chamber enclosing a mold of the plurality of molds. An automatedinjecting device, such as the injecting device 300 of FIG. 3 , may beconfigured with a barrel to receive and store a polymeric material mixedwith a blowing agent. In some examples, the injecting device may includean additional crosslinking agent (e.g., to form a SPS), a screw to pushthe SPS through the injecting device that is electronically controlled,and a nozzle adapted to couple to inlet ports in the mold. The barrel ofthe injecting device may include a temperature sensor, such as thetemperature sensor 328 of FIG. 3 to detect a temperature of thepolymeric material within the barrel of the injecting device. Thetemperature sensor and motor driving rotation of the screw may beadapted to communicate electronically with a controller, such as thecomputing device 222 of FIG. 2 , configured to receive sensoryinformation and send commands to actuators of the molding system.

At 1102, the routine includes filling the barrel of the injecting devicewith a polymeric material with a pre-set blend of small and largepellets as well as the blowing agent and crosslinking agent, providing afixed composition of the polymeric material. A barrel temperature of theinjecting device is adjusted at 1104. Adjusting the barrel temperaturemay include receiving a signal at the controller from the temperaturesensor in the barrel, the signal relaying the temperature detected inthe barrel which is also the temperature of the SPS in the barrel. Thecontroller compares the barrel temperature to a preset melt temperatureof the SPS at 1106, where the melt temperature is dependent on thecomposition of the polymeric material. For example, a look-up table maybe stored in the controller's memory with a ratio of chemical componentsof the polymeric material as an input and a corresponding melttemperature as an output that is adapted as a temperature setpoint forthe barrel temperature. A difference between the detected barreltemperature and the melt temperature may be used to correct the barreltemperature by adjusting a power output to heating devices of theinjecting device.

For example, if the temperature of the barrel is lower than the melttemperature, the power to the heating devices may be increased until thetemperature reaches the melt temperature and remains at the melttemperature for a duration of time, such as 5 seconds. As anotherexample, if the temperature in the barrel is determined to be higherthan the melt temperature, the power to the heating devices may bedecreased to allow the SPS to cool until the temperature is reduced tothe melt temperature. Adjustment of the barrel temperature to the melttemperature may include continuous intervals of increasing anddecreasing the power to the heating devices, in successively smallerincrements until the temperature of the barrel stabilizes at the melttemperature. Furthermore, exposure of the SPS in the barrel totemperatures above the melt temperature for a threshold period of time,such as 10 seconds, may result in a purging of injecting device todecrease a likelihood that overcooked material is injected into themold.

Returning to 1106, if the temperature of barrel and SPS is not at themelt temperature, the routine returns to 1104 to continue adjustingpower to the heating devices to modify the temperature of the SPS. Ifthe temperature of the barrel is detected to be at the melt temperature,the routine continues to 1108 to inject the molten SPS into the cavityof the mold while the barrel temperature is maintained at the melttemperature. At 1110, the routine includes moving the injecting deviceto another, adjacent mold. Unless the temperature of the barrel isdetected to rise above the melt temperature for more than the thresholdperiod of time, as described above, the injecting device is not purgedbetween injections to the plurality of molds, thereby reducing a periodof time for transitioning between each mold and also decreasing anamount of wasted SPS. The routine returns to 1102 to repeat routine1100.

It will be appreciated that although the pressure feedback system andthe temperature feedback system are shown as independent systems inroutines 1000 and 1100 of FIGS. 10 and 11 , respectively, other examplesmay incorporate both systems operating cooperatively. In such systemsinjection of the SPS into the molds may be delayed until both the cavitypressure is determined to match the pressure setting of the pressureprofile and the barrel temperature is at the melt temperature.Application of both pressure feedback and temperature feedback into asingle injection molding system may enhance a consistency of a polymerproduct, thereby increasing efficiency and reducing costs incurred bywasted materials.

In this way, a polymer product may be manufactured by an injectionmolding process. The injection molding process may be automated andinclude an injecting device, upstream of a plurality of molds, adaptedto couple to the plurality of molds to inject a molten polymericmaterial into a cavity of each of the plurality of molds. A nozzle ofthe injecting device may be adapted with a pressure sensor, where thepressure sensor may be included in a pressure feedback loop that relaysa pressure of the nozzle to a controller. In response, the controllermay instruct an electronically actuated screw of the injecting device torotate and push the polymeric material into the cavity at a rate thatmaintains the cavity pressure at a pressure according to a presetpressure profile. Additionally, a barrel of the injecting device,configured to store the polymeric material and including heating devicesto heat the barrel, may be adapted with a temperature sensor to detect atemperature of the polymeric material within the barrel. The temperaturesensor may be a component in a temperature feedback loop that includesrelaying the temperature of the barrel to the controller. The controllermay command adjustment of the heating of the barrel to maintain thetemperature of polymeric material at a melt temperature of the material.The pressure feedback loop may increase a uniformity of physicalproperties of the polymer product, including an expansion ratio and aconsistency of cell diameter, and also increase a repeatability of thepressure-based conditions during the injection molding process. Thetemperature feedback loop may reduce an amount of material waste arisingfrom temperature fluctuations during the injection molding process thatmay degrade the polymeric material. Overall, an efficiency andproduction output of the injection molding process is improved.

FIGS. 1-6 show example configurations with relative positioning of thevarious components. If shown directly contacting each other, or directlycoupled, then such elements may be referred to as directly contacting ordirectly coupled, respectively, at least in one example. Similarly,elements shown contiguous or adjacent to one another may be contiguousor adjacent to each other, respectively, at least in one example. As anexample, components laying in face-sharing contact with each other maybe referred to as in face-sharing contact. As another example, elementspositioned apart from each other with only a space there-between and noother components may be referred to as such, in at least one example. Asyet another example, elements shown above/below one another, at oppositesides to one another, or to the left/right of one another may bereferred to as such, relative to one another. Further, as shown in thefigures, a topmost element or point of element may be referred to as a“top” of the component and a bottommost element or point of the elementmay be referred to as a “bottom” of the component, in at least oneexample. As used herein, top/bottom, upper/lower, above/below, may berelative to a vertical axis of the figures and used to describepositioning of elements of the figures relative to one another. As such,elements shown above other elements are positioned vertically above theother elements, in one example. As yet another example, shapes of theelements depicted within the figures may be referred to as having thoseshapes (e.g., such as being circular, straight, planar, curved, rounded,chamfered, angled, or the like). Further, elements shown intersectingone another may be referred to as intersecting elements or intersectingone another, in at least one example. Further still, an element shownwithin another element or shown outside of another element may bereferred as such, in one example.

The following claims particularly point out certain combinations andsub-combinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims should be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and sub-combinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

What is claimed is:
 1. A method for a foaming process, comprising:flowing a molten polymeric material into a mold from an upstream device;receiving the molten polymeric material in a cavity of the mold; andmaintaining a repeatable, uniform pressure profile after the moltenpolymeric material is delivered into the mold.
 2. The method of claim 1,wherein maintaining the pressure profile includes adjusting the flowingof the molten polymeric material in response to a measured pressure in anozzle of the upstream device while the material is injected into themold and maintaining positive pressure on the molten polymeric materialin the mold after injection of a predetermined amount of the moltenpolymeric material into the mold is completed.
 3. The method of claim 2,further comprising removing the positive pressure on the material in themold after a duration of time elapses.
 4. The method of claim 1, whereinflowing the molten polymeric material into the mold comprises injectinga material comprising a plurality of pellets of different compositionsand/or sizes.
 5. The method of claim 1, wherein flowing the moltenpolymeric material into the mold includes forming a molten single phasesolution (SPS) from a blowing agent and the molten polymeric material,the blowing agent dissolved in the molten polymeric material.
 6. Themethod of claim 1, wherein maintaining the pressure profile of a nozzleof the upstream device is achieved by adjusting a rate that the moltenpolymeric material is injected into the cavity by the upstream device,the profile including a fixed pressure, and adapting a screw of theupstream device to be automatically adjusted, the screw controlling aninjection rate of the molten polymeric material into the cavity.
 7. Themethod of claim 1, wherein maintaining the pressure profile in a nozzleof the upstream device is further achieved by adjusting a temperature ofthe molten polymeric material.
 8. The method of claim 1, furthercomprising thermally curing the material over a consistent, reproducibleperiod of time after the molten polymeric material is released from themold and expands.
 9. A method of injection molding, comprising:maintaining a melt temperature of a polymeric material in an injectiondevice by adjusting heating of the injection device automaticallyresponsive to temperature; and injecting the polymeric material from theinjection device into a cavity of a mold.
 10. The method of claim 9,wherein maintaining the melt temperature of the polymeric materialfurther comprises determining the melt temperature for a set compositionof the polymeric material and setting a temperature control set point atthe determined melt temperature
 11. The method of claim 9, whereinadjusting heating of the injection device occurs in response tomeasurement of the temperature by a temperature sensor arranged in abarrel of the injection device.
 12. The method of claim 9, whereinmaintaining the melt temperature of the polymeric material in theinjection device includes delaying injection of the polymeric materialinto the cavity of the mold until a detected temperature of theinjection device reaches the melt temperature and adjusting atemperature of a barrel of the injecting device to maintain atemperature of the polymeric material at the melt temperature, thebarrel configured as a reservoir for the polymeric material within theinjecting device.
 13. The method of claim 12, further comprisinginitiating purging of the polymeric material stored in the barrel of theinjecting device when the material has been stored in the barrel at themelt temperature beyond a threshold period of time and when thetemperature of the polymeric material within the barrel exceeds the melttemperature, maintaining purging until the polymeric material returns tothe melt temperature.
 14. The method of claim 9, wherein maintaining themelt temperature of the polymeric material during molding of thepolymeric material is conducted in combination with maintaining auniform, reproducible pressure of the cavity of the mold.